Dye doped polymer microparticles

Abstract

Various embodiments provide dye-doped polystyrene microspheres generated using dispersion polymerization. Polystyrene microspheres may be doped with fluorescent dyes, such as xanthene derivatives including Kiton Red 620 (KR620), using dispersion polymerization. Certain functionalities, such as sodium styrene sulfonate, may be used to shift the equilibrium distribution of dye molecules to favor incorporation of the dye into the particles. Polyelectrolyte materials, such as poly(diallyldimethyl ammnonium chloride), PolyDADMAC, may be used to electrostatically trap and bind dye molecules within the particles. A buffer may be used to stabilize the pH change of the solution during dye-doped polystyrene microsphere generation and the buffer may be selected depending on the pKa of the dye being incorporated. The various embodiments may provide dye-doped polystyrene microspheres, such as KR620-doped polystyrene microspheres that are non-toxic and non-carcinogenic. These non-toxic and non-carcinogenic dye-doped polystyrene microspheres may be suitable for use in wind tunnel testing.

The invention claimed is: 
     
       1. A dye-doped polystyrene microsphere, comprising:
 a poly(styrene-co-styrene sulfonate) microsphere; 
 a shell of polyelectrolyte material surrounding the poly(styrene-co-styrene sulfonate) microsphere, wherein the polyelectrolyte comprises poly(diallyldimethyl ammonium chloride) (polyD); and 
 a fluorescent dye encapsulated within the poly(styrene-co-styrene sulfonate) microsphere, wherein the poly(styrene-co-styrene sulfonate) microsphere has a mean diameter from about 0.5 μm to about 1.5 μm, wherein the fluorescent dye has a net anionic charge, 
 wherein the weight ratio of fluorescent dye to polyelectrolyte material is from 0.33;1 to 200:1. 
 
     
     
       2. The dye-doped polystyrene microsphere of  claim 1 , wherein the poly(styrene-co-styrene sulfonate) microsphere has a mean diameter from about 1.0 μm. 
     
     
       3. The dye-doped polystyrene microsphere of  claim 1 , wherein the molar ratio of styrene sulfonate to styrene in the poly(styrene-co-styrene sulfonate) microsphere is from greater than zero to 0.2. 
     
     
       4. The dye-doped polystyrene microsphere of  claim 1 , wherein the molar ratio of styrene sulfonate to styrene in the poly(styrene-co-styrene sulfonate) microsphere is from 0.03 to 0.2. 
     
     
       5. The dye-doped polystyrene microsphere of  claim 1  wherein
 the fluorescent dye is sulforhodamine B. 
 
     
     
       6. The dye-doped polystyrene microsphere of  claim 5 , wherein dye-doped polystyrene microsphere is formed by reacting a styrene monomer, potassium persulfate, sulforhodamine B, a functionalized monomer, the polyD, and a buffer material together in an inert atmosphere. 
     
     
       7. The dye-doped polystyrene microsphere of  claim 6 , wherein the functionalized monomer is sodium styrene sulfonate and the buffer material is sodium bicarbonate. 
     
     
       8. The dye-doped polystyrene microsphere of  claim 7 , wherein the weight ratio of the polyD to sodium bicarbonate is from 0.14:1 to 6:1. 
     
     
       9. The dye-doped polystyrene microsphere of  claim 7 , wherein the weight ratio of sulforhodamine B to sodium bicarbonate is from 0.29:1 to 200:1. 
     
     
       10. The dye-doped polystyrene microsphere of  claim 1 , wherein the microsphere is produced by dispersion polymerizing a mixture comprising
 styrene, 
 styrene sulfonate, 
 poly(diallyldimethyl ammonium chloride) (polyD); and 
 a fluorescent dye haying a net anionic charge, wherein the weight ratio of fluorescent dye to polyelectrolyte material is from 0.33:1 to 200:1. 
 
     
     
       11. The dye-doped polystyrene microsphere of  claim 10 , wherein the fluorescent dye is sulforhodamine B. 
     
     
       12. The dye-doped polystyrene microsphere of  claim 10 , wherein the molar ratio of styrene sulfonate to styrene is from greater than zero to 0.2. 
     
     
       13. The dye-doped polystyrene microsphere of  claim 10 , wherein the molar ratio of styrene sulfonate to styrene is from 0.03 to 0.2.